Device to provide data as a guide to health management

ABSTRACT

A high-frequency signal generator generates a signal passing from the subcutaneous fat layer toward both the deep and shallow tissue areas. A second high-frequency signal generator generates a signal that passes primarily toward the deeper tissue. Frequency switch unit is used to select a signal of one of the frequencies. This signal is applied across whichever two of electrodes are selected by electrode switch unit  32 a. The impedance across the two limbs in contact with those electrodes is measured using the electrical potential derived at whichever two of the electrodes have been selected. From the impedance values and personal data such as weight and height, the visceral fat mass, visceral-to-subcutaneous fat ratio and other useful indicators are calculated.

FIELD OF THE INVENTION

This invention concerns a device and method to provide data about fatcontent of a human body as a guide to health management. Morespecifically, a technique of determining such values as total internalbody fat, nonfat body mass, ratio of body fat, water mass, and basicmetabolic rate are described. The present invention also describescalculating the visceral fat mass and the ratio ofvisceral-to-subcutaneous fat. Based on the results of thesecalculations, the device provides data to be used as a guide for healthmanagement.

BACKGROUND AND SUMMARY OF THE INVENTION

It is know to use four electrodes to measure the internal impedance ofthe body to determine a quantity related to internal body fat. Thisknown scheme for measuring internal impedance is pictured in FIG. 24.The equipment includes a measuring device 1 connected to electrodes 2and 3 by lead wires 6, and which apply a high-frequency signal; andelectrodes 4 and 5, which measure the resistance of the body. Thepatient is made to lie on a bed, electrodes 2 and 3 are attached to thepatient's right hand and right foot, and electrodes 4 and 5, whichmeasure the resistance of the body, are attached to the right hand andfoot close to electrodes 2 and 3, respectively. A high-frequency signalis applied to electrodes 2 and 3 by device 1, causing a current to passinto the patient's body. The potential difference between electrodes 4and 5 is measured, and the impedance of the patient's body can beobtained from this potential difference and the strength of the currentwhich was passed.

The inventor has found that devices such as shown in FIG. 24 suffer fromthe following problems.

(1) To prevent errors resulting from variation in the path of thecurrent, and to ensure that the measurement would be sufficientlyaccurate, the patient had to be lying down. The patient's feet had to bespread so that there was no danger that they would touch each other, andthe hands had to be kept well away from the torso. (2) Because of theaforesaid restrictions on the patient, and because of the difficulty ofattaching the electrodes and conducting the test, a special technicianwas needed. The patient could not perform the test without medicalsupervision, and hence the device was not suitable for use in the home.(3) Since this device is designed to be used for the treatment of agreat number of patients, it has a large key input and display unit, aprinter, an AC power supply, and other components. This makes the devicelarge and unwieldy. (4) The use of numerous electrodes with theirextension cables made preparation and cleanup difficult. (5) Just aswith an ECG, a user had to apply a conductor such as keratin cream tothe portion of the hands and feet where the electrodes were to beattached so as to minimize the effect of contact resistance. (6) Inestimating body fat by measuring impedance, impedance data for the bodyare more important than those for the hands and feet. Between the pointswhere it is measured in the existing scheme, however, the impedance ofthe hand and foot is considerably larger than that of the body. Theimpedance of joints is especially high. It is well known thatdisparities between small- and large-boned people and those with smalljoins exert profound effect on measurement results.

For example, here are some results of measuring the impedance atdifferent parts of the body.

1) Male with thick limbs: Between right hand and right foot, 350 Ω;right arm, 150 Ω; right foot, 130 Ω; thoracic region, 70 Ω

2) Female with slender limbs: Between right hand and right foot, 675 Ω;right arm, 360 Ω; right foot, 240 Ω; thoracic region, 75 Ω

3) Wrist joint: 25 to 50 Ω level

Furthermore, there are in general two types of obesity subcutaneous andvisceral. Though two patients may be similarly overweight, theviscerally obese patient will be prone to suffer from irregularities ofsugar metabolism, such as high blood sugar or high blood insulin, and offat metabolism, such as high blood cholesterol. The percentage ofvisceral fat in total internal fat is a significant criterion which canindicate whether the obesity is of the subcutaneous or visceral variety.At present, the only way to perform this test is with a large, highlyaccurate and extremely expensive device such as an X ray CT or MRIscanner. There has been a demand for a device employing a much simplermeasurement scheme.

This invention was developed in view of the inventors noting theproblems discussed above. The objective of the present invention is toprovide a device which can supply data that would be useful as a guidefor home health management. The present invention allows the patient toeasily be able to measure the impedance developed across the body. Thedevice determines the amount and ratio of visceral fat and the type ofobesity. It would be compact, light, and inexpensive, and the accuracyof its measurements would be high. An individual is able to use thedevice in the privacy of their own home.

The device to provide data as a guide to health management includes: 1)a portable main unit with grip area for the right and left hands,furnished on either end of the main unit, each of which has an electrodeto apply a high-frequency signal and an electrode to measure theresistance of the body. A foot electrode unit is connected by a cable tothe aforesaid main unit, and has electrodes to apply high-frequencysignals and electrodes to measure the electrical potential developedacross the body. The portable main unit mentioned above has a first highfrequency generator that generates a high-frequency signal which passesthrough both the shallow part of the body (where subcutaneous fat islocated) and the deeper part of body (where visceral fat is located). Asecond frequency generator generates high-frequency signal which passesmainly in the deeper part of the body. An electrode selecting deviceselects which two of the aforesaid pairs of electrodes will be used by aswitching operation.

A frequency selecting device switches frequencies to select one of theaforesaid series of high-frequency signals, and it applies them betweenthe first electrodes of the selected pairs. The impedance between thetwo pairs of electrodes from the electrical potential detected acrossthe respective second electrode in each of the pairs is detected, andthis is used to calculate the visceral fat mass based on the impedancesmeasured when the two high-frequency signals are applied. Other specificphysical data which have been entered independently, such as weight, canalso be used.

The patient uses this device by grasping the grips with both hands sothat each hand makes contact with the two electrodes in the grip. Theuser steps onto the stand, causing the sole of each foot to make contactwith the two foot electrodes. By operating the device to switchelectrodes and the device to switch frequencies, the user can easilymeasure the impedance between the various locations while in a standingposition.

The portion of the impedance attributable to the limbs can be calculatedby adding the value of the impedance between the feet (Z_(2f)) to thevalue of the impedance between the hands (Z_(2h)). These values aresubtracted from the value of the impedance between hand and foot(Z_(2b)) to obtain the impedance value for the thoracic region alone(Z_(2s)). From this impedance data and specific physical data input bythe patient, the visceral fat mass can be calculated:

Z _(2s) =Z _(2b)−(Z _(2h) +Z _(2f))/2

Another aspect of this application calculates, from the values for totalbody fat mass and visceral fat mass obtained by the device discussedabove, a value for subcutaneous fat mass, and calculates the ratio ofvisceral-to-subcutaneous fat masses. From this ratio, the presentinvention allows a determination of whether the obesity is of thesubcutaneous or visceral type.

Another aspect of this application provides elements including: 1) aportable main unit; 2) grips for the right and left hands, furnished oneither end of the main unit, each of which has an first electrode toapply a high-frequency signal and an second electrode to measure theresistance of the body; 3) a foot electrode unit, connected by a cableto the aforesaid main unit, which has electrodes to apply high-frequencysignals and electrodes to measure the electrical potential developedacross the body.

The portable main unit mentioned above is equipped with thefollowing: 1) a high frequency generator has a high-frequency signalwhich passes through both the shallow part of the body (wheresubcutaneous fat is located) and the deeper part of the body (wherevisceral fat is located), 2) an electrode selecting device includingswitches connected to establish connections that select any two of theaforesaid first and second electrodes; 3) an impedance measuring deviceto measure the impedance between the two pairs of electrodes from theelectrical potential detected across the respective second electrode ineach of the pairs; 4) a estimating device which estimates anwaist-to-hip ratio based on the data concerning impedance between thetwo pairs of electrodes measured by the device for that purpose, and onspecific physical data which have been entered independently; and 5) acalculating device to calculate visceral fat mass based on thewaist-to-hip ratio which has been estimated.

This device can, for example, measure the impedance Z_(f) between thepatient's feet, the impedance Z_(h) between the patient's hands, and/orthe impedance Z_(b) between hand and foot. From these values theimpedance Z_(s) of the thoracic region is obtained.

The device uses the impedance Z_(fs) of the hip region, which isobtained from the hand-to-hand impedance Z_(h) and the foot-to-footimpedance Z_(f), and the impedance Z_(s) of the thoracic region, toestimate a waist-to-hip ratio. It estimates the visceral fat mass andthe visceral-to-subcutaneous fat ratio using this waist-to-hip ratio,the total body fat ratio, the converted fat and other values.

The present invention allows accurate measurement of body fat ratio andvisceral fat mass. The measurement is not affected by differences in thedensity of patients' hands and feet. It provides, in a simple andreliable fashion, a measurement of visceral fat mass, which is a crucialdatum in health management.

This device allows obtaining a value for the subcutaneous fat mass aswell as the subcutaneous-to-visceral fat ratio. This allows anevaluation to be made as to whether the patient's obesity is of thesubcutaneous or visceral variety.

This device uses the various measured impedance values to estimate awastes/hip ratio, and from this estimated waist/hip ratio it calculatesan estimate of body fat mass. From this it is able to obtain a value forvisceral fat mass, a crucial datum in health management. Using thepatient's waist/hip ratio to supplement the physical data, the devicecan provide, in a simple and reliable fashion, such critical values asthe proportional index, the amount and ratio of visceral fat within thetotal fat mass, and whether the obesity is of the subcutaneous orvisceral variety.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will now be described in detailwith reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of the exterior of a device to provide dataas a guide to health management which is an ideal embodiment of thisinvention;

FIG. 2 illustrates the use of that same device;

FIG. 3 is a cross section of the foot electrode unit of the same device,taken on line A—A in FIG. 1;

FIG. 4 is a block diagram showing a portion of the circuitry in the samedevice;

FIG. 5 is a block diagram which, together with FIG. 4, illustrates thestructure of the circuits in the same embodiment;

FIG. 6 illustrates another way the device of this same embodiment mightbe used;

FIG. 7 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the first frequency and setto the mode for measuring the impedance between left hand and foot;

FIG. 8 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the same frequency and setto the mode for measuring the impedance between the hands;

FIG. 9 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the same frequency and setto the mode for measuring the impedance between the feet;

FIG. 10 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the same frequency and setto the mode for measuring the impedance between the right hand and leftfoot;

FIG. 11 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the same frequency and setto the mode for measuring the impedance between the left hand and rightfoot;

FIG. 12 is a circuit diagram illustrating the connections made when thedevice of the same embodiment is switched to the same frequency and setto the mode for measuring the impedance between both hands and feet;

FIG. 13 is a flowchart of the operations performed when the sameembodiment uses as its standard mode the measurement of the impedancebetween one hand and foot;

FIG. 14 is another flowchart of the operations performed by the sameembodiment;

FIG. 15 is another flowchart of the operations performed by the sameembodiment;

FIG. 16 is a flowchart of the operations performed when the sameembodiment uses as its standard mode the measurement of the impedancebetween both hands and feet;

FIG. 17 is another flowchart of the measurement operations performed bythe same embodiment;

FIG. 18 is another flowchart of the measurement operations performed bythe same embodiment;

FIG. 19 shows the equivalent circuits of the human body which arerelevant to measuring the impedance values used to estimate thewaist/hip ratio;

FIG. 20 is a block diagram illustrating the circuits in another idealembodiment of the device to provide data as a guide to health managementof this invention.

FIG. 21 is a flowchart of the measurement operations performed by thisdevice.

FIG. 22 is another flowchart of the measurement operations performed bythe same device;

FIG. 23 is another flowchart of the measurement operations performed bythe same device;

FIG. 24 illustrates how the impedance of the body was measured using atechnique of the prior art.

FIG. 25 shows the electrodes used on the patient's hand and foot whenthe impedance of the body was measured using a technique of the priorart.

DETAILED DESCRIPTION OF THE EMBODIMENT

FIG. 1 is a perspective view of the exterior of a device to provide dataas a guide to health management. The device of this embodiment includesmain unit 10, foot electrode unit 50, and cable 51, which connects unit10 to unit 50.

Main unit 10 has body 11 having left and right grips 12 and 13 formedintegrally on either side of body 11. The front of body 11 includespower supply switch 14; key switches 15 which are used to enter thestart command and physical characteristics of the patient such as heightand weight; and display 16, which displays the measurement results andadvisory data. Display 16 is located in the center of an area betweenleft and right handgrips 12 and 13.

Left and right grips 12 and 13 include vertical cylinders on whosesurfaces are provided electrodes 17 and 18 between which is applied ahigh-frequency signal, and electrodes 19 and 20 (see FIG. 4), whichmeasure the resistance of the body.

Foot electrode unit 50 includes flat rectangular sheet 52, on which aretwo position guides, including guide 53 for the left foot and guide 54for the right foot. Each of these guides has two electrodes. Ahigh-frequency signal is applied between electrodes 55 and 56. Theresistance of the body is measured between electrodes 57 and 58. The topsurface of the front end of sheet 52 is partially covered by housing 59.Display 60, which is used to monitor the state of the measurement, isseated in this housing. Opening 61 is located toward the front end ofsheet 52 and between the foot position guides.

FIG. 3 shows a cross section along the Line A—A in FIG. 1. Sheet 52 isconstructed of surface layer 62 and underlayer 63. Layers 62 and 63 canbe composed of PVC, PET, polyethylene, or some similar substance.Elastic protrusion 65 is located in the region corresponding to the archof the foot, in position guide 54. The two electrodes 56 and 58 areformed on elastic protrusion 65. FIG. 3 shows a cross section of theposition guide for the right foot; it should be understood that theguide for the left foot has an identical construction.

The electrodes are mounted on protrusions 64 and 65 to ensure that solidcontact with the soles of the feet when the user's feet are placed inguides 53 and 54. Protrusions 64 and 65 are constructed of an elasticsheet made of a material such as silicon rubber. Housing 59 can be madeof a material like ABS or PVC.

Cable 51 terminates in connectors 66 and 67 at respective ends thereofwhich allow connection to main unit 10 and foot electron unit 50 in sucha way that it can easily be connected or disconnected. Let us considerhow the device of this embodiment would be used to measure the impedanceof the user's body. User A would stand as shown in FIG. 2, with bothfeet in guides 53 and 54 on electrode unit 50. The user would then graspgrip 12 on main unit 10 with the left hand and grip 13 with the righthand. Measurements are taken after stretching the arms forwardhorizontally so as to hold unit 10 chest-high.

FIGS. 4 and 5 show block diagrams of the controlling circuits for thisembodiment.

The internal circuits of this device include frequency generatingcircuit 21 a, which generates a constant-current high-frequency signalwhose frequency F₁=50 KHZ (10 KHZ <f₁<100 KHZ). Another frequencygenerating circuit 21 b generates another constant-currenthigh-frequency signal whose frequency f₂=100 KHZ (40 KHZ<f₂<500 KHZ).Differential amplifier 22 receives the electrical potential signals fromelectrodes 19 and 20. The output of differential amplifier 22 isfiltered through band pass filter 23, which filters out signals offrequencies other than frequency f₀. That output is demodulated bydemodulator circuit 24, which demodulates the high-frequency signalcomponent; then A/D converter 25 converts the analog signals intodigital signals input to CPU 28. CPU 28 also has associated ROM 26 andRAM 27. CPU 28, which reads in the input from A/D converter 25 and thedata from input unit 15, including height, weight, age, sex, date andtime, and performs the operations necessary to measure the impedance,and extracts advisory data relevant to managing the patient's health.Outputs are provided to warning buzzer 29; output unit 30, whichtransmits to a printer of other peripheral device data such asmeasurement results. Battery 31 serves as the power supply for thedevice.

Electrode switch unit 32 a and frequency switch unit 32 b, supply inputsto signal generator 21 and differential amplifier 22 to switchselectively among electrodes 17, 18, 19 and 20 on grips 12 and 13 andamong electrodes 55, 56, 57 and 58 on foot electrode unit 50. This inputis connected by connector 66, cable 51 and connector 67. Switching isaccomplished by making or breaking a circuit.

Electrode switch unit 32 a and frequency switch unit 32 b can include,for example, analog switches or relays. The type of switch used mustconform to the setting of the measurement mode in CPU 28: A switch mustbe chosen which responds to the control signals for electrode andfrequency switching carried out by the CPU.

Signals of frequency f₁ can travel from the subcutaneous fat layer bothtoward the external tissue (primarily the dermis) and toward theinternal tissue (muscle, blood vessels, internal organs, bone, etc.).Signals of frequency f₂ travel from the subcutaneous fat layer primarilytoward the internal tissue.

The device described above allows data concerning physicalcharacteristics to be input via input unit 15. The weight can bemeasured by an ordinary bathroom scale 68, on which foot electrode unit50 can be placed, as shown in FIG. 6. In this case, the user steps ontofoot unit 50, weighs himself on scale 68, and enters a current bodyweight. In this embodiment, foot electrode unit 50 has an opening 61through which the user can read the weight from scale 68 while holdingmain unit 10, as shown in the drawing. A transparent window, whichallows the weight to be read, may be substituted for this opening.

The proximity of the feet when the impedance between them was beingmeasured could cause the thighs of some users to come in contact witheach other. If this happened, the measurement path would vary and affectthe accuracy of the measurements. In this embodiment, foot positionguides 53 and 54 are provided on either side of opening 61 on footelectrode unit 50, and electrodes 55, 56, 57 and 58 are placed in theseguides. The opening 61 has another, more indirect function, of ensuringa degree of separation between the feet.

The following explains the switching procedure which occurs in electrodeswitch unit 32 a in the device described above when frequency f₁ isselected. First, to measure the impedance between the right hand andright foot, the mode for that measurement is set. A switching controlsignal from CPU 28 connects the switches of electrode switch unit 32 aas shown in FIG. 4. Connection line I_(h2) from electrode 18, theelectrode which applies a high-frequency signal to the right hand, isconnected to one terminal of signal generator 21 a, and connection lineI_(f2) from electrode 55, the electrode which applies a high-frequencysignal from the left foot, is connected to the other terminal.Connection line E_(h2) from electrode 20, the electrode which measuresthe resistance of the right hand, and connection line E_(f2) fromelectrode 58, the electrode which measures the resistance of the rightfoot, are connected to the two input terminals of differential amplifier22. Connection line I_(h1) from electrode 17, the electrode whichapplies a high-frequency signal to the left hand, and connection lineE_(h1) from electrode 19, the electrode which measures the resistance ofthe left hand, are not connected to anything —they are left open.Connection line I_(f1) from electrode 55, the electrode which applies ahigh-frequency signal to the left foot, and connection line E_(f1) fromelectrode 57, the electrode which measures the resistance of the rightfoot, are also not connected to anything and are left open.

When the mode is set to measure the impedance between the left hand andfoot, a switching control signal from CPU 28 connects the switches inelectrode switch unit 32 a as shown in FIG. 7. A connection line I_(h1)from electrode 17, the electrode which applies a high-frequency signalto the left hand, is connected to one terminal of signal generator 21 a,and connection line I_(f1) from electrode 55, the electrode whichapplies a high-frequency signal to the left foot, is connected to theother terminal. Connection line E_(h1) from electrode 19, the electrodewhich measures the resistance of the left hand, and connection lineE_(f1) from electrode 57, the electrode which measures the resistance ofthe left foot, are connected to the two input terminals of differentialamplifier 22. Connection line I_(h2) from electrode 18, the electrodewhich applies a high-frequency signal to the right hand, and connectionline E_(h2) from electrode 20, the electrode which measures theresistance of the right hand, are not connected to anything and are leftopen. Connection line I_(f2) from electrode 56, the electrode whichapplies a high-frequency signal to the right foot, and connection lineE_(f2) from electrode 58, the electrode which measures the resistance ofthe right foot, are also not connected to anything and are left open.

If the mode is set to measure the impedance between the hands, aswitching control signal from CPU 28 causes the switches in electrodeswitch unit 32 a to be connected as shown in FIG. 8. Connection lineI_(h1) from electrode 17, the electrode which applies a high-frequencysignal to the left hand, is connected to one terminal of signalgenerator 21 a, and connection line I_(h2) from electrode 18, theelectrode which applies a high-frequency signal to the right hand, isconnected to the other terminal. Connection line E_(h1) from electrode19, the electrode which measures the resistance of the left hand, andconnection line E_(h2) from electrode 20, the electrode which measuresthe resistance of the right hand, are connected to the two inputterminals of differential amplifier 22. In this case, as would beexpected, connection lines I_(f1), I_(f2), E_(f1) and E_(f2), which arefor the electrodes on the feet, are not connected and are left open.

If the mode is set to measure the impedance between the feet, aswitching control signal from CPU 28 causes the switches in electrodeswitch unit 32 a to be connected as shown in FIG. 9. That is, connectionline I_(f1) from electrode 55, the electrode which applies ahigh-frequency signal to the left foot, is connected to one terminal ofsignal generator 21 a, and connection line I_(f2) from electrode 56, theelectrode which applies a high-frequency signal to the right foot, isconnected to the other terminal. Connection line E_(f1) from electrode57, the electrode which measures the resistance of the left foot, andconnection line E_(f2) from electrode 58, the electrode which measuresthe resistance of the right foot, are connected to the two inputterminals of differential amplifier 22. In this case, the rule isreversed when measuring the impedance between the hands, and connectionlines I_(h1), I_(h2), E_(h1) and E₂, which are for the electrodes on thehands, are not connected and are left open.

By setting the mode to measure the impedance between the right hand andthe left foot, a switching control signal from CPU 28 causes theswitches in electrode switch unit 32 a to be connected as shown in FIG.10. That is, connection line I_(h2) from electrode 18, the electrodewhich applies a high-frequency signal to the right hand, is connected toone terminal of signal generator 21 a, and connection line I_(f1) fromelectrode 55, the electrode which applies a high-frequency signal to theleft foot, is connected to the other terminal. Connection line E_(h2)from electrode 20, the electrode which measures the resistance of theright hand, and connection line E_(f1) from electrode 57, the electrodewhich measures the resistance of the left foot, are connected to the twoinput terminals of differential amplifier 22. Connection line I_(h1)from electrode 17, which applies a signal to the left hand, andconnection line E_(h1) from electrode 19, which measures the resistanceof the left hand, are not connected anywhere, but are left open.Connection line I_(f2) from electrode 56, which applies a signal to theright foot, and connection line E_(f2) from electrode 58, which measuresthe resistance of the right foot, are also not connected anywhere, butare left open.

When the mode is set to measure the impedance between the left hand andthe right foot, a switching control signal from CPU 28 causes theswitches in electrode switch unit 32 a to be connected as shown in FIG.11. This situation is just the opposite of that pictured in FIG. 10,with right and left hands and right and left feet exchanged. Since theconnections are just the opposite of those shown in FIG. 10, furtherexplanation is omitted.

To measure the impedance between both hands together and both feettogether, CPU 28 provides a connection detection signal which is relayedto foot electrode unit 50 via cable 51, and applies a switching controlsignal which corresponds to the command for that mode. The circuits inelectrode switch unit 32 a are connected as shown in FIG. 12. Connectionlines I_(h1) and I_(h2) from electrodes 17 and 18, the electrodes whichapply a signal to the hands, are connected to one of the terminals onsignal generator 21 a. Connection lines E_(h1) and E_(h2) fromelectrodes 19 and 20, the electrodes which measure the resistance of thehands, are connected to one of the input terminals on differentialamplifier 22. Connection lines I_(f1) and I_(f2) from electrodes 55 and56, the electrodes which apply a signal to the feet, are connected incommon to the other terminal on signal generator 21 a. Connection linesE_(f1) and E_(f2) from electrodes 57 and 58, the electrodes whichmeasure the resistance of the feet, are connected in common to the otherinput terminal on differential amplifier 22.

To apply a signal of frequency f₂ and measure the impedance between thevarious parts of the body, frequency switch unit 32 b in FIGS. 4 and 7through 12 would be operated, and signal generator 21 b would beconnected instead of signal generator 21 a.

The following description explains the principles by which body fatmass, visceral fat mass and other values can be calculated aftermeasuring the impedance between various parts of the body using thedevice described above.

Calculation of Body Fat Mass (BFM)

Body fat mass is calculated using the results of impedance measurementsmade using a signal of the first frequency. This is the signal whichwill pass from the subcutaneous fat layer to both the external tissue(primarily the dermis) and the internal tissue (muscle, blood vessels,internal organs, bone, etc.).

(1) First calculate body density (BD).

BD=a−b×W×Z ₁ /H ²

where a and b are constants determined by performing statisticalprocessing on samples extracted randomly from the parent group ofsubjects, W is weight in kilograms, and H is height in centimeters.

Formula 1.

Z₁(Ω): measured impedance(Z={square root over (R²+L +x²+L )})

(2) Next, determine ratio of body fat.

% Fat=(4.95/BD−4.5)×100

(3) From this ratio of body fat, BFM is calculated in kg.$\begin{matrix}{{BFM} = {W \times \frac{\% \quad {fat}}{100}}} & {{Formula}\quad 2.}\end{matrix}$

(4) The following calculation yields the lean body mass (LBM) orfat-free mass (FFM).

LBM=WX(1−% Fat/100)

It is standard to measure the impedance Z₁ between the right hand andfoot. However, in view of the disparities resulting from measuring thevalue from hand to hand or foot to foot, the inventors have decided thatit may be best to use the average of the values obtained by measuringthe impedance across all the limbs. $\begin{matrix}{Z_{hf}^{bar} = \quad {{\left( {Z_{{Rf} - {Rh}} + Z_{{Lh} - {Lf}}} \right)/2}\quad {or}}} \\{= \quad {\left( {Z_{{Rh} - {Lf}} + Z_{{Lh} - {Rf}}} \right)/2}}\end{matrix}$

Calculation of Visceral Fat Mass (VFM)

(1) The VFM is calculated based solely on the results of impedancemeasurements made using a signal of the second frequency. This is thefrequency which passes from the subcutaneous fat layer primarily to theinternal tissue.

VFM(kg)=aH₂/Z_(2S)+b/W+C

where a, b and c are constants determined by performing statisticalprocessing on samples extracted randomly from the parent group ofsubjects; W is weight in kilograms; H is height in centimeters; andZ_(2S) is the measured impedance (the impedance value when measured witha signal of the second frequency).

Z_(2S)=Z_(2b)−(Z_(2h)+Z_(2f))/2

Z_(2b): Impedance between hand and foot

Z_(2h): Impedance between the hands

Z_(2f): Impedance between the feet

Z_(2S): Impedance of the thoracic region

The standard measurement of Z_(2b) is made between right hand and foot.However, in view of the disparities of balance resulting from measuringthe value from hand to hand or foot to foot, the inventors decided thatit would be best to use the average of the values obtained by measuringthe impedance across all the limbs.

(2) The VFM is calculated based on the results when the impedance ismeasured using signals of both the first and second frequency. (Thestandard measurement is made from one hand to one foot.) $\begin{matrix}{{BFM} = {\frac{1}{{a \times \frac{1}{W}} - {b \times {Z_{1}/H^{2}}}} - {C \times W}}} & {{Formula}\quad 3.} \\{0035.\quad {{VFM} = {\frac{1}{{a^{\prime} \times \frac{1}{W}} - {b \times {{Z_{1}\left( {{\alpha \quad \frac{Z_{2}S}{Z_{1}s}} + \beta} \right)}/H^{2}}} + d} - {C^{\prime} \times W}}}} & {{Formula}\quad 4.}\end{matrix}$

Here a, b, c, d, a′, b′, C′, α and β are constants determined byperforming statistical processing on samples extracted randomly from theparent group of subjects; Z₁ (Ω) is the value of the impedance measuredbetween one hand and foot using a signal of the first frequency; Z_(1S)(Ω) is the value of the impedance of the thoracic region measured usinga signal of the first frequency; Z_(1S)=A₁−(Z_(1h)+Z_(1f))/2; Z_(1h) isthe impedance between the hands; Z_(1f) is the impedance between thefeet; and Z_(2S) (Ω) is the value of the impedance of the thoracicregion measured using a signal of the second frequency. Visceral FatMass (VFM), Body Fat Ratio (% Fat) and Visceral-to-Subcutaneous Ratio(V/S Ratio) are determined by the following calculations.

SFM=BFM−VFM

% Fat=BFM/W×100

V/S=VFM/SFM

A V/S ratio greater then 0.5 indicates visceral-type obesity; a V/Sratio less than 0.5 indicates the subcutaneous-type.

(3) VFM is calculated based on the results of measuring the impedanceusing signals of both the first and second frequency. (The standardmeasurement is made between both hands and both feet.)

The estimation scheme is identical to that used above in (1) and (2);however, the method of calculating Z₁, Z_(1S) and Z_(2S) differs asfollows.

Calculation of Z₁

Z₁=Z_(1W)+(Z_(1h)+Z_(1f))/4

Z_(1W): Impedance between both hands and both feet (measured using asignal of the first frequency)

Z_(1h): Impedance between the hands (measured using a signal of thefirst frequency)

Z_(1f): Impedance between the feet (measured using a signal of the firstfrequency)

Calculation of Z_(1S)

Z_(1S)=Z_(1W)−(Z_(1h)+Z_(1f))/4

Calculation of Z_(2S)

Z_(2S)=Z_(2W)−(Z_(2h)+Z_(2f))/4

Z_(2W): Impedance between both hands and both feet (measured using asignal of the second frequency)

Z_(2h): Impedance between the hands (measured using a signal of thesecond frequency)

Z_(2f): Impedance between the feet (measured using a signal of thesecond frequency)

The operation of this system will now be described with reference to theflowcharts in FIGS. 13, 14 and 15. The impedance as measured between onehand and one foot shall be used as a standard.

When power supply switch 14 is turned on, various preparatory proceduresare performed. The RAM is initialized, the circuit elements and displayelements are checked, and so on (Step, hereafter ST 1). The user enters,via input unit 15, his or her characteristic physical data, includingheight, weight, age, sex, and waist-to-hip ratio, as well as the dataand time (ST 2). Until all the data have been input, the device standsby (ST 2 and ST 3). When data entry is completed, the CPU determineswhether the foot electrode unit is connected (ST 4) by determiningwhether there is a connection detection signal from connector 66 or 67in the circuit shown in FIGS. 4 and 5.

If the determination in ST 4 was “no”, a message will be displayed ondisplay 16 to the effect that the foot electrodes must be connected, toinform the user (ST 5). If the determination in ST 4 was “yes”,frequency f₁ is selected, voltage switch unit 32 b and signal generator21 a are chosen, and the voltage selection flag is set (ST 6). Electrodeswitch unit 32 a is set to the mode for measuring impedance between theright hand and foot, and the identification code is set to select righthand and right foot (ST 7).

When the setting of the switches is completed, the device stands byuntil the start switch on input unit 15 is actuated (ST 8). After theswitches have been set, a command such as “Actuate start switch” canappear on display 16 to encourage the user to operate the key. When thestart switch is turned on, there is a time delay of several seconds (ST9), after which buzzer 29 or display 16 is used to inform the user thatmeasurement has begun (ST 10). The time delay in ST 9 after the startswitch is turned on should be sufficient to allow the user to graspgrips 12 and 13 completely and correctly and to ensure proper footplacement into position guides 53 and 54.

When impedance is measured, a check is made as to whether the valueobtained is stable and in the correct range (ST 11 and 12). If the valueis not stable, a message such as “Hands and feet must make good contactwith the electrodes” can be shown on display 16 and buzzer 29 can warnthe user (ST 13). If the value measured is found to be correct andstable in ST 12, the measurement operation is executed (ST 14), and adetermination is made as to whether the signal being applied has thefirst frequency (ST 15). Since at this time the determination will be“yes”, flow proceeds to a determination as to whether the selection codefor the electrode switch unit has been set to “right hand, right foot”(ST 16). Since this determination will also be “yes” at this time, themeasurement result, i.e., the impedance value which was measured, willbe stored in the memory area as right hand-right foot impedanceZ_(Rh−Rf) (ST 17). Electrode switch unit 32 a will be switched to lefthand-left foot mode, and the identification code will be changed toselect left hand-left foot (ST 18). Program flow now returns to ST 11,and the impedance Z_(Lh−Lf) between the left hand and foot is measuredin ST 11 through 14. The determination in ST 15 of whether the signalapplied was of the first frequency will again be “yes”, just as it wasthe first time through; however, the determination in ST 16, whether theidentification code for the electrode switch unit has been set to righthand-right foot, will now be “no”, since the code was changed to lefthand-left foot in ST 18. Flow then proceeds to ST 19.

In ST 19, the right hand-right foot impedance value Z_(Rh−Rf) is readout of the memory area where it was stored and added to the lefthand-left foot impedance value Z_(Lh−Lf) to calculate the average valueZ₁, which is equal to (Z_(Rh−Rf)+Z_(Lh−Lf))/2 (ST 20). The average valueZ₁ is stored in the memory area (ST 21), frequency switch unit 12 b isswitched to the second measurement frequency, and the frequencyselection flag is reset (ST 22). The resetting of this flag indicatesthat the second frequency, frequency f₂, has now been selected.

Once the frequency selection flag has been reset in ST 22, flow returnsto ST 11, and impedance Z_(Lh−Lf) is measured between the left hand andleft foot in ST 11 through 14. The determination in ST 15, whether thesignal applied was of the first frequency, will be “no”, so program flowpasses to ST 23, which queries whether the identification code for theelectrode switch unit is set to left hand-left foot. The answer here is“yes”, so the impedance value Z_(Lh−Lf) which was measured is stored atthis time in the memory area (ST 24). Flow now reverts to the righthand-right foot measurements mode, changes the identification code backto the code to select right hand-right foot (ST 25), and returns to ST11.

In ST 11 through 14, the impedance Z_(Rh−Rf) between right hand andright foot is measured by applying a signal of frequency f₂. Thedetermination in ST 15 and 23 will be “no”, so flow proceeds to ST 26,which queries whether the code is that for right hand-right foot. Whenthe result is “yes”, the impedance value Z_(Lh−Lf) which was previouslystored in the memory area (ST 27) is read out. The right hand-right footvale Z_(Rh−Rf) and the left hand-left foot value Z_(Lh−Lf) are used tocalculate the average value Z_(2b) using Z_(2b)=(Z_(Rh−Rf)+Z_(Lh−Lf))/2(ST 28). This average value Z_(2b) is stored in the memory area (ST 29),electrode switch unit 32 a is switched to the hand-to-hand mode, theidentification code is changed to select hand-to-hand (ST 30), andreturns to ST 11.

ST 11 through 14 measure the impedance Z_(2h) between the hands. Sincethe determinations in ST 15, 23 and 26 are all “no”, flow proceeds to ST31, where the process determines if the identification code selectshand-to-hand. The answer is “yes”, so the hand-to-hand impedance valueZ_(2h) which was measured is stored in the memory area (ST 32).Electrode switch unit 32 a is switched to foot-to-foot measurement mode,the identification code is changed to select foot-to-foot (ST 33), andflow returns to ST 11.

ST 11 through 14 measure the impedance Z_(2f) between the feet. Sincethe determinations in ST 15, 23, 26 and 31 are all “no”, flow proceedsto ST 34, where the average hand-foot impedance value Z_(2b) and thehand-to-hand impedance value Z_(2h) are read from the memory. Fromimpedance values Z_(2b) and Z_(2h) and the foot-to-foot impedance valueZ_(2f), the impedance Z_(2S) of the thoracic region is calculated usingZ_(2S)=Z_(2b)−(Z_(2h)+Z_(2f))/2 (ST 25). The personal data, includingweight, height, and so on, are read out of the memory area (ST 36). Thepersonal data and the calculated value Z_(2S) are substituted in theformula to estimate VFM, and the VFM is calculated (ST 37).

The average value Z₁ for hand-foot impedance as measured with a signalof the first frequency is read out of the memory area (ST 38). Thepersonal data and value Z₁ are substituted in the formula to estimatebody fat ratio, and the body fat ratio is calculated (ST 39). Body fatmass is calculated using the formula BFM−W×% Fat/100 (where W is weight)(ST 40). Subcutaneous fat mass is calculated using the formulaSFM=BFM−VFM, and the visceral-to-subcutaneous ratio is obtained byV/S=VFM/SFM (ST 41).

A determination is made as to whether the V/S ratio is less than 0.5 (ST42) If V/S is less than 0.5, a determination is made that the obesity isof the subcutaneous type (ST 42). If the ratio exceeds 0.5, the obesityis judged to be of the visceral type (ST 43). The fact that allmeasurements and calculations have been completed is conveyed by display16 and buzzer 29 (ST 45). The results of the calculations and advisorydata are displayed on display 16 or output to the exterior via acommunication device (ST 46).

The following explains the operation of an embodiment in which thestandard measurement mode is between both hands and feet, with referenceto the flowcharts shown in FIGS. 16, 17 and 18.

The initial processing performed when power supply switch 14 is actuatedinclude ST 51 through 56, and are identical to ST 1 through 6 ofmeasuring the impedance across one hand and foot. In ST 57 electrodeswitch unit 32 a is set to measurement mode for both hands-both feet,and the identification code is set to both hands-both feet. When thesetting of the switches has been completed, the device stands by untilthe start switch on input unit 15 is actuated (ST 58). When the startswitch is turned on, there is a time delay identical to that experiencedwhen measuring impedance between one hand and foot (ST 59). The user isinformed that measurement has begun (ST 60), and the impedance Z_(1W)between both hands and both feet is measured through the processingperformed in ST 61 through 64.

A determination is made as to whether the signal applied was of thefirst frequency (ST 65). Since initially this determination will be“yes”, flow proceeds to the determination of whether the selection codefor the electrode switch unit is set for both hands-both feet (ST 66).This determination is also “yes” at this time, so the impedance Z_(1W)between both hands and feet is stored in the memory area (ST 67).Electrode switch unit 32 a is switched to hand-to-hand mode, and theidentification code is changed to that which selects hand-to-hand (ST68). Flow returns to ST 11, where the impedance Z_(1h) between the handsis measured in ST 61 through 64. The determination in ST 65, whether thesignal applied is of the first frequency, is still “yes”, but thedetermination is ST 66, whether the identification code for theelectrode switch unit is set to select both hands-both feet, is now“no”, since the code was changed to select hand-to-hand in ST 68, soflow proceeds to ST 69. The determination in ST 69, whether theselection code is set to hand-to-hand, is “yes”, so the measurementresult Z_(1W) is stored in the memory area (ST 70). The electrode switchunit is changed to foot-to-foot mode (ST 80), the identification code ischanged to select foot-to-foot, and flow returns to ST 61.

In ST 61 through 64, the impedance Z_(f) between the feet is measured.The determinations in ST 65, 66 and 69 are all “no”, so flow proceeds toST 71. In this step, impedance Z_(1W), measured between both hands andfeet, and impedance Z_(1h), measured between the hands, are read out ofthe memory area where they have been stored. Using Z_(1W), Z_(1h), andimpedance Z_(1f), measured between the feet, Z₁ is obtained by solvingZ=Z_(1W)+(Z_(1h)+Z_(1f))/4, and Z_(1S) is obtained by solvingZ_(1S)=Z_(1W)−(Z_(1h)+Z_(1f))/4 (ST 72). Z₁ and Z_(1S) are stored in thememory area (ST 73), the frequency switch unit is switched to select thesecond measurement frequency, frequency f₂, and the frequency selectionflag is reset (ST 74). The electrode switch unit is changed tohand-to-hand measurement mode, the identification code is changed toselect hand-to-hand measurement mode (ST 68), and flow returns to ST 61.

In ST 61 through 64, the impedance Z_(2h) between the hands is measuredusing a signal of frequency f₂. The determinations in ST 65 and 75 areboth “no”, so flow proceeds to ST 78, which required a determination asto whether the code is set to select hand-to-hand impedance. The answeris “yes”, so the measurement result, i.e., impedance Z_(2h) measuredbetween the hands, is stored in the memory area (ST 79). The electrodeswitch unit is changed to foot-to-foot measurement mode, theidentification code is changed to select foot-to-foot (ST 80), and flowreturns to ST 61.

In ST 61 through 64, the impedance Z_(2f) between the feet is measured.The determination in ST 65, 75 and 78 are all “no”, so flow proceeds toST 81 where impedance Z_(2W) measured between both hands and feet, andimpedance Z_(2h) measured between the hands, are read out of the memoryarea where they have been stored. Using Z_(2W), Z_(2h), and impedanceZ_(2f), measured between the feet, the impedance Z_(2S) of the thoracicregion can be calculated by solving Z_(2S)=Z_(2W)−(Z_(2h)+Z_(2f))/4 (ST82). The personal data, including weight, height, and so on, are readout of the memory area (ST 83). The personal data and the calculatedvalue Z_(2S) are substituted in the formula to estimate VFM, and the VFMis calculated (ST 84). In the same way, BFM is calculated using the BFMestimation scheme (ST 85). Weight W is read out, and the body fat ratiois calculated by solving % Fat=(BFM/W)×100 (ST 86). The subcutaneous fatmass is calculated by SFM=BFM−VFM, and the visceral-to-subcutaneousratio is obtained by V/S=VFM/SFM (ST 87).

Just as in ST 42 through 46 when measuring one hand and foot, adetermination is made as to whether V/S is less than 0.5 (ST 88). If itis, the obesity is judged to be of the subcutaneous type (ST 90). If V/Sexceeds 0.5, it is judged to be of the visceral type (ST 89). The factthat all measurements and calculations have been completed is conveyedby display 16 and buzzer 29 (ST 91). The results of the calculations andadvisory data are displayed on display 16 or output via a communicationdevice (ST 92).

It is well known that the ratio of body fat and body fat mass calculatedusing the impedance measured between parts of the body with standardvoltage measurements, as described above, and the W/H (waist-to-hip)ratio can be used to estimate the ratio of visceral-to-subcutaneous, fatmass, the visceral fat mass, and other useful values. This is discussedin further detail herein.

The impedance across the various parts of the human body is representedin an equivalent fashion in FIG. 19. The impedance Z_(fS) (=Z_(fS1),=Z_(fS2)), which is found within the impedance Z_(f) measured betweenthe feet, contains data concerning the hips (H). The impedance Z_(S)measured in the center of the thoracic region contains data concerningthe waist.

The arms and legs generally develop in balance with each other. Both thearms and legs of a large-boned person will be thick. Similarly, amuscular person will generally have arms and legs which are equallydeveloped. This makes it possible to extract Z_(fS) by subtracting Z_(h)from Z_(f) and dividing. It follows, then, that

W/H=Z_(S)/Z_(fS)

Z_(S)=Z_(b)−(Z_(h)+Z_(f))/2

Z_(fS)=α₁Z_(f)−β₁Z_(h)+γ₁, and Z_(h)>Z_(hS1)=Z_(hS2)

α₁, β₁ and γ₁ are constants

From the above, W/H is calculated. $\begin{matrix}{{W/H} = {{Z_{s} \cdot \frac{Z_{h}}{{\alpha_{2}Z_{f}} + \beta_{2}} \cdot f}\quad \left( {{Height}\quad {and}\quad {weight}\quad {data}} \right)}} & {{Formula}\quad 5.}\end{matrix}$

Here f (height and weight data) is revised to correspond to personaldata concerning height and weight, and α₂ and β₂ are constants.

A partial circuit diagram for the device of this embodiment, whichestimates the W/H ratio using the impedance values measured and uses thevarious impedance values and the W/H ratio to estimate VFM, thevisceral-to-subcutaneous fat ratio and other values, is shown in FIG.20. Unlike the device pictured in FIGS. 4 and 5, the device of thisembodiment has only one frequency switch unit, 32, which corresponds tounit 32 a in the earlier embodiment. The rest of this device, includingthe circuitry beyond differential amplifier 22, which is not shown, isidentical to the previous embodiment, and hence a detailed explanationis omitted.

The operation of this embodiment of the device will be explained withreference to the flowchart shown in FIGS. 21, 22 and 23.

The initial power-up processing in ST 101 through 105 is the same asthat in ST 1 through 5 in FIGS. 13 through 15. After ST 104 verifiesthat good contact is being made with the foot electrodes, electrodeswitch 32 is set to measurement mode for right hand-right foot, and theidentification code is set to right hand-right foot (ST 106).

When the setting of the switches is completed, the device stands byuntil the start switch on input unit 15 is actuated (ST 107). When thisswitch is turned on, the time delay processing is performed (ST 108),and the user is informed that measurement has begun (ST 109). Theimpedance Z_(Rh−Rf) between right hand and foot is measured in ST 110through 113.

Next, the CPU determines whether the selection code for the electrodeswitch unit is set for right hand-right foot (ST 114). Since thisdetermination will be “yes” at this time, the measurement result, i.e.,the impedance value which was measured, will be stored in the memoryarea as right hand-right foot impedance Z_(Rh−Rf) (ST 115), electrodeswitch unit 32 will be switched to left hand-left foot mode, and theidentification code will be changed to select left hand-left foot (ST116). Processing flow returns to ST 110, and the impedance Z_(Lh−Lf)between the left hand and foot is measured in ST 110 through 113. Thedetermination in ST 114, whether the selection code for the electrodeswitch unit is set for right hand-right foot, will now be “no”, sincethe code was changed to left hand-left foot in ST 116, so flow proceedsto ST 117.

ST 117 makes a determination whether the selection code is set for lefthand-left foot. Since the answer is now “yes”, the impedance Z_(Rh−Rf)between right hand and foot is read out of the memory area where it wasstored (ST 118). Along with impedance Z_(Lh−Lf) between left hand andfoot, this value is used to calculate the average value Z_(b) by solvingZ_(b)=(Z_(Rh−Rf)+Z_(Lh−Lf))/2 (ST 119). This average value Z_(b) isstored in the memory area (ST 120), the electrode switch unit isswitched to hand-to-hand mode, the identification code is changed toselect hand-to-hand (ST 121), and flow returns to ST 110.

The impedance Z_(h) between the hands is measured in ST 110 to 113.Since the determination in ST 114 and 117 will be “no”, flow proceeds toST 122 which determines whether the selection code indicateshand-to-hand. Since the answer will be “yes”, the measurement result,i.e., the impedance Z_(h) measured between the hands, is stored in thememory area (ST 123). The electrode switch unit is switched tofoot-to-foot measurement mode, the identification code is switched tofoot-to-foot (ST 124), and program flow returns to ST 110.

The impedance Z_(f) between the feet is measured in ST 110 to 113. Sincethe determinations in ST 114, 117 and 122 will all be “no”, flow movesto ST 125, where the average impedance Z_(b) between hands and feet andthe impedance Z_(h) between the hands is read out of the memory area.From impedance values Z_(b), Z_(h) and Z_(f), the impedance between thefeet, the impedance Z_(S) of the thoracic region is obtained by solvingZ_(S)=Z_(b)−(Z_(h)+Z_(f))/2 (ST 126). Next, the personal data includingweight and height are read out of the memory area (ST 127). Bysubstituting these personal data and Z_(S), Z_(h) and Z_(f) in theformula to estimate the W/H ratio, the ratio (ST 128) is obtained. Andby substituting the average impedance Z_(b) between hand and foot andthe personal data in the formulas to estimate body fat ratio and bodyfat mass, % Fat and BFM (ST 129) are calculated. The personal data, W/Hratio, body fat ratio and BFM yield the following. $\begin{matrix}{{V/S} = {\frac{VFM}{SFM} = {{\alpha \left( {W/H} \right)} + \beta}}} & {{Formula}\quad 6.}\end{matrix}$

Here α and β are constants. SFM and BFM are calculated bySFM−BFM/(1+V/S) and VFM=BFM−SFM. The visceral-to-subcutaneous ratio V/S,the subcutaneous fat mass SFM and the visceral fat mass VFM arecalculated (ST 130).

Just as in ST 42 through 46 in FIGS. 13 through 15, a determination ismade as to whether the V/S ratio is less than 0.5 (ST 131). If it isless, a determination is made that the obesity is of the subcutaneoustype (ST 133). If the ratio exceeds 0.5, the obesity is judged to be ofthe visceral type (ST 132). When all measurements and calculations havebeen completed, display 16 and buzzer 29 indicate completion (ST 134).The results of the calculations and advisory data are displayed ondisplay 16 or output to the exterior via a communication device (ST135).

Although only a few embodiments have been described in detail above,those having ordinary skill in the art will certainly understand thatmany modifications are possible in the preferred embodiment withoutdeparting from the teachings thereof.

All such modifications are intended to be encompassed within thefollowing claims.

What is claimed is:
 1. A body fat detecting device, comprising: a firstpair of electrodes and a second pair of electrodes; a main unit havingfirst and second body contact elements at respective ends of the mainunit, each of said first and second body contact elements includingthereon an electrode from each of said first pair of electrodes and saidsecond pair of electrodes; a signal generator configured to supply ahigh frequency signal to said first pair of electrodes; a determinationdevice which determines an impedance between said second pair ofelectrodes; a calculating device which calculates fat data based on saidimpedance; and a display for displaying results calculated by saidcalculating device and located on said main unit.
 2. A body fatdetecting device according to claim 1 further comprising means forallowing entry of individual data about a subject, and wherein saidcalculating device is responsive to said individual data for calculatinga fat mass.
 3. A body fat detecting device according to claim 1 whereinsaid signal generator is configured to supply a first high frequencycurrent, wherein said first high frequency current travels primarilytowards external tissue, and a second high frequency current, whereinsaid second high frequency current travels primarily towards internaltissues.
 4. A body fat detecting device according to claim 3 whereinsaid calculating device calculates a ratio between visceral fat mass andsubcutaneous fat mass and uses said ratio to determine a type of fatnessof the subject.
 5. A body fat detecting device, comprising: a first pairof electrodes and a second pair of electrodes; a main unit having firstand second body contact elements at respective ends thereof, each ofsaid first and second body contact elements comprising an electrode fromeach of said first pair of electrodes and said second pair ofelectrodes; a signal generator configured to supply a high frequencysignal to said first pair of electrodes; a determination device whichdetermines an impedance between said second pair of electrodes;verification means for verifying if a value of said impedance is in aproper range and is stable; a calculating device which calculates fatdata based on said impedance if said verification means verifies saidvalue of said impedance is in a proper range and is stable; and adisplay for displaying results calculated by said calculating device andlocated on said main unit.
 6. A body fat detecting device according toclaim 5, wherein said body contact elements comprise top units at topends of said main unit and bottom units at bottom ends of said mainunit.
 7. A body fat detecting device according to claim 5, wherein saidmeans for determining an impedance comprises means for providing a timedelay processing after a start key on said main unit is initiated inorder to ensure that said body contact elements are properly contacted.8. A body fat detecting device according to claim 7, further comprisingmeans for allowing entry of individual data about a subject, and whereinsaid calculating means is responsive to said individual data forcalculating a fat mass.
 9. A body fat detecting device according toclaim 7, wherein said signal generator comprises first means forsupplying a first high frequency current, wherein said first highfrequency current travels primarily towards external tissue, and secondmeans for supplying a second high frequency current, wherein said secondhigh frequency current travels primarily towards internal tissue.
 10. Abody fat detecting device according to claim 7, wherein said calculatingdevice calculates a ratio between visceral fat mass and subcutaneous fatmass and uses said ratio to determine a type of obesity.
 11. A body fatdetecting device, comprising: a first pair of electrodes and a secondpair of electrodes; a main unit having first and second body contactelements at respective ends thereof, each of said first and second bodycontact elements comprising an electrode from each of said first pair ofelectrodes and said second pair of electrodes; a signal generatorconfigured to supply a high frequency signal to said first pair ofelectrodes; a determination device which determines an impedance betweensaid second pair of electrodes; verification means for verifying if avalue of said impedance is in a proper range and is stable in order toensure that said first and second body contact elements are properlyengaged; a calculating device which calculates a fat mass based on saidimpedance if said verification means verifies said value of saidimpedance is in a proper range and is stable; and a display fordisplaying results calculated by said calculating device and located onsaid main unit.